Null pointer used.

Address coverity report of null pointer being dereferenced.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4381)

crypto/ct/ct_log.c

@@ -199,7 +199,7 @@ int CTLOG_STORE_load_file(CTLOG_STORE *store, const char *file)
     CTLOG_STORE_LOAD_CTX* load_ctx = ctlog_store_load_ctx_new();
 
     if (load_ctx == NULL)
-        goto end;
+        return 0;
     load_ctx->log_store = store;
     load_ctx->conf = NCONF_new(NULL);
     if (load_ctx->conf == NULL)